include/linux/objtool.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _LINUX_OBJTOOL_H
   3 #define _LINUX_OBJTOOL_H
   4
   5 #include <linux/objtool_types.h>
   6
   7 #ifdef CONFIG_OBJTOOL
   8
   9 #include <asm/asm.h>
  10
  11 #ifndef __ASSEMBLY__
  12
  13 #define UNWIND_HINT(type, sp_reg, sp_offset, signal)    \
  14         "987: \n\t"                                             \
  15         ".pushsection .discard.unwind_hints\n\t"                \
  16         /* struct unwind_hint */                                \
  17         ".long 987b - .\n\t"                                    \
  18         ".short " __stringify(sp_offset) "\n\t"                 \
  19         ".byte " __stringify(sp_reg) "\n\t"                     \
  20         ".byte " __stringify(type) "\n\t"                       \
  21         ".byte " __stringify(signal) "\n\t"                     \
  22         ".balign 4 \n\t"                                        \
  23         ".popsection\n\t"
  24
  25 /*
  26  * This macro marks the given function's stack frame as "non-standard", which
  27  * tells objtool to ignore the function when doing stack metadata validation.
  28  * It should only be used in special cases where you're 100% sure it won't
  29  * affect the reliability of frame pointers and kernel stack traces.
  30  *
  31  * For more information, see tools/objtool/Documentation/objtool.txt.
  32  */
  33 #define STACK_FRAME_NON_STANDARD(func) \
  34         static void __used __section(".discard.func_stack_frame_non_standard") \
  35                 *__func_stack_frame_non_standard_##func = func
  36
  37 /*
  38  * STACK_FRAME_NON_STANDARD_FP() is a frame-pointer-specific function ignore
  39  * for the case where a function is intentionally missing frame pointer setup,
  40  * but otherwise needs objtool/ORC coverage when frame pointers are disabled.
  41  */
  42 #ifdef CONFIG_FRAME_POINTER
  43 #define STACK_FRAME_NON_STANDARD_FP(func) STACK_FRAME_NON_STANDARD(func)
  44 #else
  45 #define STACK_FRAME_NON_STANDARD_FP(func)
  46 #endif
  47
  48 #define ANNOTATE_NOENDBR                                        \
  49         "986: \n\t"                                             \
  50         ".pushsection .discard.noendbr\n\t"                     \
  51         ".long 986b\n\t"                                        \
  52         ".popsection\n\t"
  53
  54 #define ASM_REACHABLE                                                   \
  55         "998:\n\t"                                                      \
  56         ".pushsection .discard.reachable\n\t"                           \
  57         ".long 998b\n\t"                                                \
  58         ".popsection\n\t"
  59
  60 #else /* __ASSEMBLY__ */
  61
  62 /*
  63  * This macro indicates that the following intra-function call is valid.
  64  * Any non-annotated intra-function call will cause objtool to issue a warning.
  65  */
  66 #define ANNOTATE_INTRA_FUNCTION_CALL                            \
  67         999:                                                    \
  68         .pushsection .discard.intra_function_calls;             \
  69         .long 999b;                                             \
  70         .popsection;
  71
  72 /*
  73  * In asm, there are two kinds of code: normal C-type callable functions and
  74  * the rest.  The normal callable functions can be called by other code, and
  75  * don't do anything unusual with the stack.  Such normal callable functions
  76  * are annotated with the ENTRY/ENDPROC macros.  Most asm code falls in this
  77  * category.  In this case, no special debugging annotations are needed because
  78  * objtool can automatically generate the ORC data for the ORC unwinder to read
  79  * at runtime.
  80  *
  81  * Anything which doesn't fall into the above category, such as syscall and
  82  * interrupt handlers, tends to not be called directly by other functions, and
  83  * often does unusual non-C-function-type things with the stack pointer.  Such
  84  * code needs to be annotated such that objtool can understand it.  The
  85  * following CFI hint macros are for this type of code.
  86  *
  87  * These macros provide hints to objtool about the state of the stack at each
  88  * instruction.  Objtool starts from the hints and follows the code flow,
  89  * making automatic CFI adjustments when it sees pushes and pops, filling out
  90  * the debuginfo as necessary.  It will also warn if it sees any
  91  * inconsistencies.
  92  */
  93 .macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 signal=0
  94 .Lhere_\@:
  95         .pushsection .discard.unwind_hints
  96                 /* struct unwind_hint */
  97                 .long .Lhere_\@ - .
  98                 .short \sp_offset
  99                 .byte \sp_reg
 100                 .byte \type
 101                 .byte \signal
 102                 .balign 4
 103         .popsection
 104 .endm
 105
 106 .macro STACK_FRAME_NON_STANDARD func:req
 107         .pushsection .discard.func_stack_frame_non_standard, "aw"
 108         .long \func - .
 109         .popsection
 110 .endm
 111
 112 .macro STACK_FRAME_NON_STANDARD_FP func:req
 113 #ifdef CONFIG_FRAME_POINTER
 114         STACK_FRAME_NON_STANDARD \func
 115 #endif
 116 .endm
 117
 118 .macro ANNOTATE_NOENDBR
 119 .Lhere_\@:
 120         .pushsection .discard.noendbr
 121         .long   .Lhere_\@
 122         .popsection
 123 .endm
 124
 125 /*
 126  * Use objtool to validate the entry requirement that all code paths do
 127  * VALIDATE_UNRET_END before RET.
 128  *
 129  * NOTE: The macro must be used at the beginning of a global symbol, otherwise
 130  * it will be ignored.
 131  */
 132 .macro VALIDATE_UNRET_BEGIN
 133 #if defined(CONFIG_NOINSTR_VALIDATION) && \
 134         (defined(CONFIG_MITIGATION_UNRET_ENTRY) || defined(CONFIG_MITIGATION_SRSO))
 135 .Lhere_\@:
 136         .pushsection .discard.validate_unret
 137         .long   .Lhere_\@ - .
 138         .popsection
 139 #endif
 140 .endm
 141
 142 .macro REACHABLE
 143 .Lhere_\@:
 144         .pushsection .discard.reachable
 145         .long   .Lhere_\@
 146         .popsection
 147 .endm
 148
 149 #endif /* __ASSEMBLY__ */
 150
 151 #else /* !CONFIG_OBJTOOL */
 152
 153 #ifndef __ASSEMBLY__
 154
 155 #define UNWIND_HINT(type, sp_reg, sp_offset, signal) "\n\t"
 156 #define STACK_FRAME_NON_STANDARD(func)
 157 #define STACK_FRAME_NON_STANDARD_FP(func)
 158 #define ANNOTATE_NOENDBR
 159 #define ASM_REACHABLE
 160 #else
 161 #define ANNOTATE_INTRA_FUNCTION_CALL
 162 .macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 signal=0
 163 .endm
 164 .macro STACK_FRAME_NON_STANDARD func:req
 165 .endm
 166 .macro ANNOTATE_NOENDBR
 167 .endm
 168 .macro REACHABLE
 169 .endm
 170 #endif
 171
 172 #endif /* CONFIG_OBJTOOL */
 173
 174 #endif /* _LINUX_OBJTOOL_H */